Safety syringe for needleless injector

ABSTRACT

A disposable syringe for use in a needleless injector includes a tubular body with an open rear end, a closed front end containing an injection orifice, a chamber in the body for receiving a liquid and a plunger slidable in the chamber for pushing the liquid out of the orifice. A tip is provided on the inner end of the plunger for separation from the remainder of the plunger to block the orifice when the plunger is retracted after an injection, whereby the syringe cannot be re-used.

BACKGROUND OF THE INVENTION

This invention relates to a disposable syringe, and in particular to adisposable syringe for single use in a needleless injector.

U.S. Pat. No. 5,190,523 issued to I. Lindemayer on Mar. 3, 1990discloses a disposable syringe and a needleless injector. There are manyother patents and published patent applications relating to needlelessinjectors, including U.S. Pat. No. 7,357,915, issued to K. Menassa onApr. 15, 2008. In spite of the large amount of activity in the field,there still exists a need for a safety syringe for a needleless injectorwhich can be used once and only once. The present invention is believedto meet such need.

SUMMARY OF THE INVENTION

Accordingly, the invention provides a disposable syringe for aneedleless injector which includes a tubular body defining a fluidchamber, i.e. a chamber for receiving a fluid such as a medicine, thebody having an open end for slidably receiving a piston and a closedend; a coupler for connecting the body to the discharge end of aninjector barrel, an orifice in said closed end of the body fordischarging fluid from the chamber when the piston is pushed towards theorifice, a separable tip on an end of the piston in the body, whereby,when the piston is pushed fully into the body to eject fluid therefrom,the tip separates from the piston and remains in the body in an orificesealing position, preventing re-use of the syringe.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below in greater detail with reference to theaccompanying drawings, wherein:

FIG. 1 is a partly sectioned side view of one end of a pistol-typeneedleless injector containing a disposable syringe in accordance withthe invention;

FIG. 2 is an exploded, isometric view of the disposable syringe of FIG.1;

FIG. 3 is a longitudinal sectional view of the syringe of FIGS. 1 and 2;

FIG. 4 is a front view of the syringe of FIGS. 1 to 3;

FIG. 5 is a longitudinal sectional view of one end of the syringe ofFIGS. 1 to 4;

FIGS. 6 and 7 are longitudinal sectional views showing the operation ofhte syringe of FIGS. 1 to 4;

FIG. 8 is a longitudinal sectional view of the syringe of FIGS. 1 to 4with a guard;

FIG. 9 is an isometric view of a second embodiment of the syringe;

FIG. 10 is a side view of the syringe of FIG. 9;

FIG. 11 is an exploded isometric view of the syringe of FIGS. 9 and 10;

FIG. 12 is an isometric view of one end of an injector barrel and thesyringe of FIGS. 9 to 11 with parts omitted;

FIGS. 13 to 15 are longitudinal sectional views showing the operation ofthe syringe of FIGS. 9 to 11;

FIGS. 16 to 18 are longitudinal sectional views of a third embodiment ofthe syringe;

FIGS. 19 to 21 are longitudinal sectional views of a fourth embodimentof the syringe of the present invention;

FIG. 22 is a longitudinal sectional view of one end of a needlelessinjector incorporating a disposable nozzle in accordance with theinvention;

FIG. 23 is an exploded, longitudinal sectional view of the injector andnozzle of the FIG. 22;

FIG. 24 is an isometric view of a spacer used in the injector of FIGS.22 and 23;

FIG. 25 is an isometric view of the nozzle of FIGS. 22 and 23; and

FIG. 26 is a longitudinal sectional view of one end of the nozzle ofFIG. 25 and a second embodiment of a guard used thereon.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1, a syringe in accordance with the present inventionwhich is indicated generally at 1 is intended for use in a needlelessinjector 2, which in this case is in the shape of a pistol. The injector2 includes a body with a handle 3 extending downwardly fromapproximately the center thereof. The body is defined by upper and lowercylinders 5 and 6, respectively, which contain most of the remainingelements of the injector. For the most part, the elements of theinjector 2 are the same as or similar to the elements of the injectordescribed in above-mentioned U.S. Pat. No. 7,357,915.

A brass piston 7 is slidably mounted in the cylinder 5. The piston 7 isgenerally cup-shaped, including a rear recess for receiving acylindrical, permanent magnet 8. A tubular barrel 10 is connected to thefront end of the cylinder 5. The piston 7 is used to drive a plunger 11mounted on the front end of the piston 7. Movement of the piston 7 andthe plunger 11 are controlled by a trigger 13, which is protected by atrigger guard 14, and a plunger 15 extending out of the cylinder 6 forcontrolling a valve (not shown) in the cylinder 6. The valve is similarto that disclosed by the above-referenced U.S. Pat. No. 7,357,915.Forward movement of the plunger 11 in the barrel 10 causes operation ofthe syringe 1.

As best shown in FIGS. 2 and 3, the syringe 1 includes a tubular body 16for slidably receiving a piston or plunger 17. The body 16 has an openinner end 18 (when mounted in the barrel 10 of the injector) and aclosed outer end 19. An annular flange 20 near the outer end 19 limitsmovement of the body 16 into the barrel 10. Threads 22 on the body 16behind the flange 20 engage the internally threaded discharge end 23 ofthe injector barrel 10 when mounting the syringe in the injector. Fluid,typically medicine, from a chamber 24 in the body 16 is dischargedthrough an orifice 25 in the outer end 19 of the body 16. An externallythreaded recess 27 in the end 19 forms part of a luer lock forconnecting a conventional externally threaded needle, catheter or otherdevice (not shown) to the syringe. Longitudinally extending ribs 28 onthe cylindrical outer end 19 of the body 16 facilitate gripping of thebody when screwing the syringe into the injector barrel 10. Radiallyextending teeth 29 on the annular periphery of the closed end 19 of thebody 16 prevent rotation of the body when the injector is in use, i.e.when the orifice 25 or the outer end 19 of the body 16 is pressedagainst the skin during an injection.

In one embodiment, the plunger 17 includes an elongated body 30 ofcruciform cross section throughout most of its length with reinforcinggussets 31. A pair of spaced apart discs 32 and 33 are provided at andnear the inner end of the body 30. The disc 32 is engaged by the plunger11 during an injection. The disc 33 slides into the narrow discharge endof the barrel 10 during injection and limits movement of the plunger 17into the body 16 of the syringe. A third disc-shaped reinforcing rib 35is provided roughly halfway between the rib 33 and the cylindrical outerend 36 of the plunger body 30. A skirt 37 flares outwardly from anannular recess 38 (FIG. 2) in the outer end of the body 30 for sealingengagement with the passage 24.

As best shown in FIG. 5, the discharge end 40 of the chamber 24 and thecorresponding end 41 of the plunger 17 have essentially the same shape.The end 40 of the passage 24 tapers to the orifice 25 and includes anannular projection or restriction 42. The end 41 of the plunger 17 has ataper identical to that of the end 40 of the passage 24, and an annulargroove 44 (line of weakness) near the tip 45 thereof. A longitudinallyextending slot 46 is provided in the tip 45 so that the tip can compresswhen encountering the restriction 42.

In operation, the orifice end of the syringe is connected to a medicinebottle (not shown) and the plunger 17 is retracted to draw medicine intothe passage 24. When the plunger 17 is pushed into the body 16 (FIG. 6),the tip 45 is jammed into the end 40 of the passage 24, and theprojection 42 enters the groove 44. When the plunger 17 is retracted(FIG. 7), the narrow tip 45 of the plunger remains in position againstthe orifice 25 while the remainder of the plunger is retracted. Thus,the orifice 25 is permanently blocked from the inside, prevent re-use ofthe syringe.

As shown in FIG. 8, a guard 50 can be mounted on the end 19 of thesyringe body 16. The guard 50 performs a dual function, viz it preventsspray from the injection site, and spaces the orifice 25 from theinjection site. For such purpose, the guard 50 is shaped like a cap witha circular outer end 51 and a cylindrical side wall 52. A central hole54 in the end 51 permits passage of fluid from the orifice 25 to aninjection site. Because the orifice 25 is spaced from the injection siteby the thickness of the end 51, the force of the fluid is less than ifthe orifice 25 was pressed against the injection site. Thus, the guard50 is used when making subcutaneous injections. An externally threadedsleeve 58 integral with the end 51 mates with the threaded recess 27 inthe end 19 of the body 16 to connect the guard 50 to the syringe.Projections or ribs 59 are gripped when screwing the syringe into thebarrel 10 of the injector. A thin, cup-shaped shield 60 extendsoutwardly from the rear end of the side wall 52 for surrounding aninjection site.

Referring to FIGS. 9 to 11, a second embodiment of the inventionincludes a tubular body 62 with a pair of arcuate ears 63 at the innerend 64 thereof. The ears 63 are used in a bayonet coupling for mountingthe syringe in the end of an injector barrel 66, one end 67 of which isshown in FIG. 12. The interior of the open end 67 of the barrel 66includes a pair of opposed recesses 68 for receiving the ears 63. Theears 63 pass through the recesses 68, and then the body 62 is rotated toreleasably lock the syringe in the barrel 66. When the body 62 isrotated to the locked position, a small projection 69 on the outer endof one ear 63 enters a notch 70 in the end of the barrel 66. As in thefirst embodiment of the invention, the outer end 71 of the body 62contains an orifice 72 and a threaded recess 73 for use in a luerconnector.

A plunger 74 is slidably mounted in the body 62. The plunger 74 includesan elongated body 75 of cruciform cross section reinforced bydisc-shaped ribs 76. A large disc 78 on the inner end 79 of the body 75supports the body for sliding in the injector barrel 66. A cylindricalhead 80 on the outer end of the plunger body 75 contains a groove 81,carrying an O-ring 82 (FIGS. 13 to 15) for sealing the plunger 74 in thebody 62 of the syringe.

The outer discharge end 83 of a chamber 84 in the syringe body 62 isconical. As illustrated in FIGS. 13 to 15, when the plunger 74 is movedfrom a retracted position (FIG. 13) to the extended, injection position(FIG. 14), a conical head 86 on the outer end 80 of the plunger isjammed into the conical end 83 of the chamber 84. Because the head 86 isconnected to the remainder of the plunger body 75 by a very narrow,frangible neck 87, when the plunger 74 is retracted, the head 86 remainsin the conical end 83 of the chamber 84. Thus, the orifice 72 is sealed,preventing re-use of the syringe. In order to ensure separation of thehead 86, the diameters of the conical discharge end 83 of the chamber 84and the head 86 must be such that the head is retained in the passage byfriction; i.e. they must be the same size or the head can be slightlylarger in diameter than the passage.

In a third embodiment of the invention (FIGS. 16 to 18) the outer end 80of the plunger 74 includes a cylindrical recess 90 holding thecylindrical inner end of a generally conical head 91. The head 91contains an annular groove 92 (FIG. 16) and the generally conicaldischarge end 94 of the chamber 95 contains an annular projection 96. Asin the case of the head 86 in the second embodiment of the invention(FIGS. 13 to 15), when the plunger 74 is extended (FIG. 17), the head 91is jammed into the end 94 of the chamber 95. The projection 96 mateswith the recess 92 in the head 91. Thus, when the plunger 74 isretracted (FIG. 18), the head 91 remains in the discharge end 94 of thechamber 95 is blocking the orifice 72.

With reference to FIGS. 19 to 21, in a fourth embodiment of theinvention, the outer end 80 of the plunger 74 includes a narrowdiameter, cylindrical projection 98 carrying a head 99, which isseparable from the end 80. For such purpose, the head 99 includes arecess 100 in the inner end thereof. During an injection, the conicaltip 102 of the head 99 is jammed into the conical discharge end 103 ofthe medicine chamber 105 to seal the orifice 72.

FIGS. 22 to 26 illustrate disposable nozzle assemblies in accordancewith the invention. The nozzle assemblies of FIGS. 22 to 26 are intendedfor use on a disposable injector of the type illustrated in U.S. Pat.No. 7,357,915.

The discharge end 109 of the barrel 110 of the earlier injector includesa piston assembly 111 for forcing liquid through a valve 112 defined bya flexible, hollow valve stem 113 in the inlet end 114 of a nozzle 115,and a flexible rubber valve head 116. A circular stainless steel spacer118 is sandwiched between the valve head 116 and an annular shoulder 119in the barrel 110. As best shown in FIG. 24, the spacer 118 includesfour diametrically opposed notches 120 or a plurality of such notches inthe periphery thereof. The notches 120 permit the flow of liquid aroundthe valve head 116. When the liquid in the barrel 110 is subjected to asufficiently high pressure, liquid flows through the notches 120compressing the valve 113, whereby liquid from the barrel 110 flows intothe nozzle 115.

The nozzle 115 is defined by a tubular body 121 with a passage 122therethrough. A pair of diametrically opposed holes 124 in the inner orinlet end of the body 121 are normally closed by the valve stem 113. Thebody 121 is slidable in the open discharge end of the barrel 110. Anannular groove 125 (FIG. 25) in the body 121 receives an O-ring 126 forsealing the nozzle in the barrel 110. An annular flange 127 on themiddle of the body 121 is sandwiched between the outlet end of thebarrel 110 and an internally threaded cap or nut 128 mounted on theexternally threaded outer end 109 of the barrel 110. Liquid isdischarged from the nozzle 115 through an orifice 130 in the otherwiseclosed outer end of the body 121.

The outer end of the body 121 includes external threads 131 for matingwith the internally threaded tubular body 134 of a guard 135. Liquidexiting the orifice 130 is discharged through an aligned orifice 136 inthe body 134. A generally hemispherical shield 137 extends outwardlyfrom the inner or rear end of the guard body 134.

The guard 139 of FIG. 26 is similar to the guard 135 of FIGS. 22 and 23,except that the outer end 140 of the body 134 is thicker and includes acylindrical recess 141. Thus, when the outer end 140 is pressed againstan injection site (not shown), there is a gap between the orifice 136and the injection site.

It will be appreciated that with the apparatuses of FIGS. 22 to 26,following an injection, it is only the guard which needs to be replaced.

1. A disposable syringe for use in a needleless injector comprising atubular body having an open end and a closed end, a chamber in said bodyfor receiving a fluid; a plunger slidable through said open end intosaid chamber; an orifice in the closed end of the tubular body fordischarging fluid from the body when the plunger is pushed towards theorifice; a separable tip on an end of the piston for plugging saidorifice when the plunger is pushed into said passage during aninjection; and a retainer for separating the tip from the remainder ofthe plunger when the plunger is retracted following an injection.
 2. Thedisposable syringe of claim 1, wherein said retainer includes a conicaldischarge end of the passage behind and connected to the orifice; anannular projection in said discharge end of the passage; a conical tipon said plunger for mating with said discharge end of the passage; andan annular groove in said tip of said plunger for receiving theprojection, said groove defining a frangible area of the tip; whereby,when the conical plunger tip is jammed into the discharge end of thepassage and then retracted, the conical tip of the plunger breaks in thearea of said frangible area and remains in the discharge end of thepassage blocking the orifice.
 3. The disposable syringe of claim 1,wherein said retainer includes a conical discharge end of said passagein the barrel; a conical tip on said plunger for mating with saiddischarge end of the passage, said tip having the same or slightlylarger dimensions than the conical discharge end of the passage; and afrangible neck connecting the conical tip to the remainder of theplunger, whereby, when the tip of the plunger is pushed into thedischarge end of the passage, the tip becomes jammed in said dischargeend and, when the plunger is retracted, the neck is broken and the tipremains in the passage, blocking the orifice.
 4. The disposable syringeof claim 1, wherein said retainer includes a conical discharge end ofsaid passage behind the orifice; an annular projection in said dischargeend of the passage; a recess in an inner discharge end of said plunger,a conical head removably mounted in said recess for mating with saiddischarge end of the passage; an annular groove in said head forreceiving the projection, whereby, when the conical plunger tip ispushed into the discharge end of the passage and then retracted, thehead is retained by the projection and remains in the discharge end ofthe barrel.
 5. The disposable syringe of claim 1, wherein said retainerincludes a conical discharge end of said passage behind the orifice; aprojection on an inner, discharge end of said plunger; a head removablymounted on said projection; a conical tip on the discharge end of saidhead for mating with said conical discharge end of the passage, said tiphaving the same or a slightly larger diameter along its length than thedischarge end of the passage, whereby, when the plunger is pushed intothe body of the syringe, the tip becomes jammed in the conical dischargeend of the passage, and, when the plunger is retracted, the tip remainsin the passage, blocking the orifice.
 6. The disposable syringe of claim1, including an annular flange on the discharge end of the tubular bodyfor limiting movement of the syringe into a needleless injector barrel.7. The disposable syringe of claim 6, including threads on the tubularbody behind the flange for engaging an internally threaded discharge endof a needleless injector barrel when mounting the syringe in theinjector.
 8. The disposable syringe of claim 6 including an internallythreaded recess in the discharge end of the body surrounding the orificefor connecting an externally threaded end of a needle or catheter. 9.The disposable syringe of claim 8 including radially extending teeth onthe discharge end of the body surrounding the recess for preventingrotation of the syringe when the body is pressed against skin during aninjection.
 10. The disposable syringe of claim 1 including a pair ofdiametrically opposed ears on the open, rear end of the body for matingwith complementary recesses in a front end of a needleless injectorbarrel to form a bayonet coupling between the syringe and the injector.